"Man will not always stay on Earth; the pursuit of light and space will lead him to penetrate the bounds of the atmosphere, timidly at first, but in the end to conquer the whole of solar space."

For the Soviet Union, these famous words of the early 20th-century space prophet Konstantin Tsiolkovsky are more than a romantic vision. The scenarios he sketched have been, and continue to be, a program for action. Implementing it, the USSR has become by far the most active nation in making practical use of space as well as, at least temporarily, taking the lead in manned spaceflight.

This point in worth dwelling on briefly for it gives a useful perspective on the remarkable stamina and consistency of the Soviet space program. These two qualities form that program's principal challenge to the United States.

In spite of encountering far more serious setbacks than the US space effort has ever suffered, the Soviets have persevered. They had to forfeit the moon race (and there is evidence they were indeed racing) to the US. In the late 1960s and early 1970s, they had to abandon efforts to develop a giant Saturn-5 -class rocket after several blew up on the pad. They lost four cosmonauts during space missions. Their effort to establish the Salyut space station series had catastrophic early failures, including loss of control of two of the vehicles in orbit.

Yet the Soviets persisted and even increased their efforts. Their space funding has been rising 3 to 5 percent annually in real terms in recent years. They have again taken up development of a giant rocket with 10 million to 14 million pounds liftoff thrust, compared with 7.5 million pounds for the now-defunct US Saturn 5. They have perfected the Salyut to become the test bed for a permanent space station whose crews can be rotated and which can be resupplied indefinitely.

In short, the Soviets give every appearance of pursuing long-term strategic goals in space -- goals for which there is general agreement within their hierarchy. Beyond hard-nosed assessment of commercial, military, and scientific payoffs, there seems to be a consensus throughout Soviet society that humanity's destiny is to expand outward into the solar system and that the Soviet Union should take the lead. This is often referred to by space officials, cosmonauts, and other as fulfilling Tsiolkovsky's dream.

Thus the Soviet space effort has broad-based cultural and philosophical support which helps it weather setbacks. This is something the United States space program never has enjoyed.

Tsiolkovsky's vision was quite practical. He anticipated commercial development. He foresaw orbital flight. And he assumed it to be sensible first to acquire a versatile capacity for such flight and then to establish as permanent space station from which manned flights farther out could be staged.

These are goals the Soviets consistenly have pursued to the point where they now are poised to set up that space station, which reportedly would be permanently manned by rotating crews of a dozen cosmonauts. This station, or its immediate successor, could become a staging ground for an expedition to Mars , in the estimation of Western analysts as well as according to hints from Soviet officials.

Oleg Gazenko, a leading Soviet expert in space medicine, put it this way last November when speaking to the International Academy of Astronautics conference in Bonn: "It is difficult to give an exact date for a flight to Mars. But I think the basic prerequisites for such a flight exist now. . . . Whether the flight happens in 10, 15 or 20 years, I cannot say. But I believe it will be before the year 2000."

Also, in commenting on the successful long-duration missions of the Salyut 6 space station, the Soviets releaded a statement saying in part: "A considerable increase in the duration of manned spaceflights produces an economic effect and helps one to realistically assess the feasibility of manned spaceflights to the closet planets. In the future, and perhaps in the not too distant future, such flights will no doubt be accomplished." It added: "One can express a firm conviction that the launching of Salyut 6 station has paved the way for manned flights to other planets in the solar system."

Given the secrecy that envelops all aspects of the Soviet space effort, it is difficult to assess its exact dimensions, strengths, and weaknesses. However, certain facts to some extent speak for themselves to indicate that the Soviets do have a formidable space capability.

To see that the Soviet Union is the most active spacefaring nation, you have only to note that, from the orbiting of the first sputnik on Oct. 4, 1957, through the end of last year, the Soviets carried out 1,339 launches which at least put a payload into orbit compared with 587 such launches for the US. Those payloads included military, commercial, scientific, experimental, and manned missions.

In recent years, the imbalance in launches has been striking. The Soviets consistently have conducted several times as many launches as has the US. Last year, for example, there were 89 Soviet launches compared with 13 for the US. Moreover, at least two of the Soviet rockets carried eight separate payloads, while several others had some kind of seccondary payload riding piggyback. Also , 10 of the missions were to the Salyut 6 space station. Six carried cosmonauts , while four were made by unmanned Progress resupply freighters.

The USSR now has a global network of communications, weather, and resource satellites, to say nothing of military reconnaissance vehicles and its ominous tests of "killer" spacecraft that can destroy other satellites. In one notable demonstration of space capacity, they sent 10 reconnaissance spacecraft with recoverable film packs on what were called Earth resources missions in 1979. These are believed to have gathered data on the world wheat crop before Soviet buyers entered the grain market in a year of poor Soviet harvests.

It is against his background of a highly active, competent, and consistently sustained space effort that the Soviet manned spaceflight program should be seen. Again, a few general statistics give some perspective.

When Cosmonauts Leonid I. Popov and Valerity V. Ryumin ended their recordingmaking 185-day tour in Salyut 6 last Oct. 11, Soviet cosmonauts had accumulated a combined 45,969 hours of space experience compared with 22,503 hours for US astronauts. Cosmonaut Ryumin, himself, who also had been on the earlier 175-day Salyut mission, had accumulated just four days short of a year in space. His two major missions were far longer than the 84-day duration of the longest US Skylab tour.

Since one of the great unknowns of manned spaceflight is the adaptability of humans, to the space environment, this experience differential is meaningful. The Soviets have had an opportunity to learn a great deal more about humans in space than have American space biologists. There have been problems of adaptation. Some cosmonauts have had trouble walking and speaking when returning to the gravitational environment of Earth's surface. However, such problems seem to be overcome by sensible work, exercise, and rest regimens while in orbit. Part of the payoff of the Salyut long-duration flights has been determining such regimens.

For example, Cosmonaut Popov said that having a varied activity program helps maintain a sense of well-being in the cramped spaceship. Ryumin agreed and stressed the importance of such pre-flight training as workouts in a water tank, where the experience of being neutrally buoyant helps prepare for weightlessness.

There appear to be no human obstacles to space station duty, to judge from what has been reported of the Soviet experience. However, whether physical or mental problems would show up with sustained space duty of more than half a year still is unknown. Referring to this, Popov said, "If . . . an expedition to Mars were being prepared and it should be necessary to hold a year-long stay in space, I think we would readily agree to such work."

There is another statistic that has interesting implications. As of the end of last year, there had been 28 visits to Salyut 6 since it went into orbit Sept. 29, 1977. Of these, 15 were Soyuz spaceships that carried cosmonauts who successfully docked with the space station and worked within it. Soyuz 25, the first ship up, had to abort its mission after an unsuccessful docking attempt because it ran low on battery power.Soyuz 33 aborted because of engine trouble. There were two unmanned Soyuz flights as well -- Soyuz 34, a return vehicle sent to cosmonauts already in orbit, and Soyuz T, which carried out a test flight of an updated Soyz design. Finally, there were 11 missions by unmanned Progress resupply vessels.

Clearly, the Salyut-Soyuz-Progress combination has been thoroughly proved out as the prototype of a permanent space station system. The Soviets have worked hard to achieve this.

As noted earlier, there were a number of setbacks. Some early Salyuts malfunctioned in orbit. In 1971 three cosmonauts died when their Soyuz 11 capsule lost pressurization during reentry. This forced the Soviets to restrict subsequent Soyuz missions to two cosmonauts each so that the crew could wear their bulky space suits. Not until late last year, with the roomier upgraded Soyuz T, have three cosmonauts been able to ride into space together. Now the Soviets again talk of having two pilots and a mission specialist in Soyuz crews.

Also, the Salyut program is by no means a wholly civilian effort, although the Soviets have played down its military side. As has been pointed out by veteran space analyst James Oberg -- a computer specialist with the US National Aeronautics and Space Administration, who follows the Soviet program on his own time:

"The first Salyut, plus launches in 1972, 1973, 1975, and 1977, was of the 'civilian' variety, characterized by civilian crewmen, high altitudes, and scientific instrumentation. The 'military' Salyuts, which were launched in 1973 , 1974, and 1976, have had all-military crews, lower orbits for better ground observation, generally undisclosed instrumentation, and special canisters for the return of film to Earth automatically."

Thus the Soviets have built up a manned spaceflight system that has impressive civilian and military capability. They are using it for a variety of experiments, including studying manufacture of special materials that can be made in extremely pure states under weightless conditions. They are using it for goodwill, also, with a guest cosmonaut program that includes members from a number of Communist and other favored countries. And, even though Salyut 6 has more work to do, they are talking already of its successor.

The Salyuts have two docking ports -- one forward and one aft. According to spacecraft designer Konstantin Feoktistov, Soviet designers have been thinking of providing salyuts with 6 to 8 such docking ports and are looking ahead to what he has called "the modular construction of orbital stations."

Whether they also are working on a Soviet space shuttle is unclear. Such reports as have appeared seem to refer to a winged vehicle that would be far less versatile than the US shuttle and might not even be reusable. US analyst Oberg has pointed out that the Soviets don't really need a shuttle. They already have a fairly versatile system. Also, they have a range of relatively cheap rockets which may soon be augmented by a Saturn-5-class booster. They can do what they need to do without a shuttle.

Looking at this formidable capability, the National Security Council warned President Jimmy Carter in late 1979:

"The currently operational military and civil Soviet manned program could provide them with significant scientific, technical, political, and strategic advances. . . ."

The continued successes of the Salyut program since then only underscores this warning.

The space shuttle, officially known as the Space Transportation System, can do much to help the US meet this challenge. But it will not by itself provide the experience or the capacity needed to establish a permanent working space station, let alone go to Mars.

Perhaps, indeed, it will be the Soviets who first step onto the Red Planet and fulfill Tsiolkovsky's dream. If so, observers James Oberg, ". . . they are the ones who deserve to, since they believe in it and are sacrificing for it."

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